The present invention relates generally to the processing of hazardous waste, and, particularly, the invention relates to a method and system for processing drummed or containerized hazardous waste using pyrolysis and steam reforming.
The use of high temperature reactors for the processing of drummed hazardous compounds is known to convert such materials into compounds that are acceptable for either reuse or release into the environment. These reactors employ various processes to achieve this result. Two such processes are pyrolysis and steam reforming.
Pyrolysis is well known for use in processing hazardous waste, including organic and radioactive wastes. For several decades, pyrolysis has been used in converting organic materials, such as biomass and municipal solid waste, into a synthesis gas, otherwise called syngas, that is rich in carbon monoxide, carbon dioxide, hydrogen, and light hydrocarbons. The syngas can thereafter by used to drive an engine, turbine, or boiler to general power. Modern pyrolysis systems have been built to process municipal solid waste at rates reaching several hundred tons of waste per day.
Steam reforming is also a well-known process for use in treating hazardous materials. Steam reforming has been used commercially for over a century for the production of syngas for the generation of power. Steam reforming has further been used as a source of hydrogen for use in chemical synthesis. For example, a majority of oil refineries have steam-reforming units to convert fuels into a source of hydrogen. Indeed, most fuel cell applications, including automobiles, also use steam reforming to generate a hydrogen rich gas from a liquid hydrocarbon fuel.
The pyrolysis and steam reforming processes are, therefore, well developed and well understood. Further, it is known to employ steam reforming and pyrolysis for use in processing hazardous wastes in drums, which avoids the bulk handling of these wastes. However, current methods employing these processes suffer from a number of disadvantages. For example, a majority of the methods using pyrolysis typically introduce hot gases into the system to directly react with the waste materials so that they are reacted. If hot, high volume heating gases are present in a method, the gas flow and gas composition within the system are more difficult to control. Other methods employing pyrolysis use internal combustion fired heat. These methods are generally incineration processes, which are becoming unacceptable from an environmental standpoint. Incinerators and related processes that utilize open-flame combustion fall under stringent and comprehensive air pollution laws that typically render the incinerators economically infeasible.
Methods for processing hazardous wastes that use steam reforming are also disadvantageous in that they are typically operated under oxygen starved or reducing conditions. Therefore, these methods may require auxiliary energy to fully react the material. Further, a separate unit may be required in these methods to oxidize the organics, carbon monoxide, and hydrogen to carbon dioxide and water so that release of gases to the environment can occur.
Accordingly, there remains a need for a process that does not have the limitations and shortcomings of the above described methods for processing hazardous wastes in drums through the use of pyrolysis and steam reforming.